Extrinsic Hair Aging: Cosmetic Treatment Concepts and
Biophysical Test Methods
Stephan Bielfeldt, Marianne Brandt, Klaus-Peter Wilhelm
proDERM Institute for Applied Dermatological Research GmbH, Kiebitzweg 2, 22869 Schenefeld/Hamburg, Germany
Introduction
Extrinsic hair aging focuses on hair alterations during the hairs‘ lifetime on the head. The oldest part of a hair is the tip and therefore, the maximum age-related
damage is found there. The longer the hair, the older it is and the more hair damage has accumulated due to chemical treatment, washing, combing, UV-light
and other sources. Today, multi-purpose active ingredients are included in new hair care products to counter such age-dependent changes. Mainly, actives like
conditioners or UV-filters are designed to protect from the sources of hair damage. In case the damage has already occurred, products like repair serums are
marketed that glue split ends and sticking-out cuticle flakes. In the macroscopic view, it is important that the products are effective to shape the tip region back
to a good alignment of hairs.
Methods
As a quick and reproducible approach, multiple combing of hair tresses in a combing apparatus is an established method (3-5) to produce a defined status of extrinsic damage. On such artificially weathered hair swatches, the efficacy of hair care products can easily be tested. Usually, the weight loss of the tresses treated with multiple combing or weighing of hair debris that gathers
in the combing machine is used to quantify the hair damage. We compare this method to a new procedure of image analysis of the broken hair fragments (Figure 1). Hair tress damage by multiple combing is also a suitable method to artificially produce the frayed look of the hair tips. We report a method to quantify this frayed look of the tips by image analysis (Figure 2).
For all experiments, flat-bundled bleached natural hair swatches were washed with a standard shampoo (12.5 % sodium lauryl ether sulphate with 2 Mol EO in water). Ten tresses were washed with
standard shampoo and treated with a marketed conditioner product after overnight-drying. Measurements of hair breaking damage were performed after 2000, 5000 and 10000 combings. The fallen-out snippets of broken hair were weighed and images of the debris were taken under even illumination. The precision of the two methods to quantify the debris were compared (Figure 3 and 4).
Results
A
B
Correlation of Gravimetrical Assessment and Image Analysis to
Determine the Amount of Broken Hairs
100000
y = 5856.4x
R² = 0.9359
90000
C
Image Analysis - Hairs [pxl]
80000
D
70000
60000
50000
40000
30000
20000
10000
Figure 3 The effect of adherent products cannot be neglected when
measuring broken hair debris by weighing, especially when only
low hair damage has to be measured precisely. After 2,000 combings of the shampooed tresses, almost identical amounts of broken hair snippets were measured by image analysis and weight.
This was not found for the conditioner treatment. The image analysis documented approximately 30 % less hair debris compared to
the weighing. We assume that the amount of conditioner that was
attached to the debris led to an overestimation of hair breakage
when weighing.
Figure 1 Procedure of image analysis: Original black and white photograph where hair snippets appear white on the dark background (Images A, B magnified). By grey value segmentation the snippet is identified as a 2D-object (Image C). A skeleton algorithm is used to reduce
the snippet to a string of 1 pixel thickness. The number of pixels of all
skeletonized snippets is calculated and taken as an equivalent of the
total amount of broken hair (Image D). Contrary to the weight of snippets, this result is only reflecting the amount of broken hairs unaffected from test products adherent to the snippets.
0
0
2
4
6
8
10
12
14
16
Gravimetrical Assessment - Hairs [mg]
Figure 4 A high correlation (N : 60 data pairs; R² = 0.936) between
weight of debris and pixel count of the image analysis was found for
combing debris of hair swatches.
Figure 2 Shadow images and image analysis were used to quantify the effect
of the frayed look of the hair tips. The left shadow images show hair in the
original state (1) and frayed (3) by multiple combing. Image 4 displays the
segmented frayed hair as increased grey area compared to 'non-frayed' (2).
The larger this area the more pronounced is the fraying. To obtain reproducible results of volume, the tress is turned ten times in steps of 18°. Images of
each angle are analyzed and the resulting areas averaged to obtain a result
that reflects the volume.
1
2
3
4
Conclusion
The investigation of hair breakage and fraying of hair tips in multiple combing experiments on hair swatches is a swift and well-standardized approach to investigate important parameters of extrinsic hair aging. The model allows simulation of combing-related hair aging just in hours that naturally develops over years on the head of the consumer. Further experiments to correlate the results to
counts of split ends and electron microscopy of cuticle damage are desirable to obtain a more complete image of measurement parameters for extrinsically aged hair.
Literature
1.
Thibaut, S., et al. Chronological ageing of human hair keratin fibres. J Cosmet Sci. 32 (6). 422-434 (2010)
2.
Wiesche, E. S., et al. Prevention of hair surface aging. J Cosmet Sci 62 (2). 237-249 (2011)
3.
Robbins C, Kamath Y. Hair breakage during combing IV. Brushing and combing hair. J Cosmet Sci. 58 (6). 629-636 (2007)
4.
Cooper N, Short J, Szadurski J, Turek J. Assessment of the effect of hair care products on hair strengthening. Proc 14th Cong Int Fed Soc Cosmet Shem. 2. 1125- 1133 (1986)
5.
Haake HM, Marten S, Seipel W, Eisfeld W. Hair breakage--how to measure and counteract. J Cosmet Sci. 60 (2). 143-151 (2009)